US7819106B2 - Engine control apparatus using signal with level changing with engine operation - Google Patents

Engine control apparatus using signal with level changing with engine operation Download PDF

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US7819106B2
US7819106B2 US12/068,116 US6811608A US7819106B2 US 7819106 B2 US7819106 B2 US 7819106B2 US 6811608 A US6811608 A US 6811608A US 7819106 B2 US7819106 B2 US 7819106B2
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edge
signal
irregular
region
interval
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US20080189024A1 (en
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Haruhiko Kondo
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Denso Corp
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Denso Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/009—Electrical control of supply of combustible mixture or its constituents using means for generating position or synchronisation signals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/14—Timing of measurement, e.g. synchronisation of measurements to the engine cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2403—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially up/down counters

Definitions

  • the present invention relates to apparatuses for controlling an engine based on a signal having a level changing with operations of the engine.
  • Engine control units for vehicles use a crank signal whose signal level varies in a predetermined same direction at regular rotation angles (regular crank angles) of an engine crankshaft.
  • crank signal is measured by a crankshaft sensor connected to an engine control unit, the measured crank signal is input to the engine control unit.
  • the engine control unit Based on the input crank signal, the engine control unit works to identify a rotational position (crank position) of the crankshaft; this rotational position has a resolution higher than that obtained based on the angular intervals of the crankshaft.
  • the engine control unit measures a time interval from when a predetermined-directed level change appears in the crank signal and a next predetermined-directed level change appears therein. On the basis of the measured time interval, the engine control unit generates an angle clock as an operation clock; this angle clock consists of a train of clock pulses whose clock cycle is determined by dividing, by a predetermined multiplication number, the measured time interval.
  • the clock cycle of the angle clock is determined by dividing, by the predetermined multiplication number, the time interval between temporally adjacent predetermined-directed level changes in the crank signal. For this reason, the crank position of the crankshaft is shifted by an angle at every clock cycle of the angle clock; this angle is defined as an angular resolution of the rotation of the crankshaft.
  • the number of active edges, such as rising edges, of the angle clock have been counted for each cycle of the engine. This makes possible that the crank position of the crankshaft corresponding to each of the count values is identified with a high resolution.
  • crank signal includes a regular region in which its signal level varies in a predetermined same direction at regular rotation angles of the crankshaft and an irregular region in which its signal level varies in the predetermined same direction at a rotation angle greater than the regular rotation angle.
  • the engine control unit When the engine control unit generates an angle clock whose clock cycle is determined by dividing, by a predetermined multiplication number, a measured time interval between temporally adjacent predetermined-directed level changes in the irregular region of the crank signal, the clock cycle of the angle clock during the irregular region of the crank signal is longer than that of the angle clock during the regular region of the crank signal.
  • the deviation between an actual crank position of the crankshaft and a crank position thereof determined based a count value of the angle clock during the irregular region of the crank signal may cause an event, such as fuel injection, ignition, or the like, to occur at an abnormal timing. This may contribute to improper engine control.
  • Japanese Patent Application Publication No. 2001-200747 discloses an engine control unit.
  • the engine control unit is designed to divide, by a predetermined ratio, a measured time interval between temporally adjacent predetermined-directed level changes in the irregular region of the crank signal.
  • the predetermined ratio is a ratio of a time interval between temporally adjacent predetermined-directed level changes in the irregular region of the crank signal to that between temporally adjacent predetermined-directed level changes in the regular region of the crank signal.
  • the engine control unit divides, by the predetermined ratio, a measured time interval between temporally adjacent predetermined-directed level changes in the irregular region of the crank signal to obtain a corrected time interval. Thereafter, the engine control unit generates a corrected angle clock whose clock cycle is determined by dividing, by a predetermined multiplication number, the corrected time interval.
  • the angle clock generated based on the measured time interval before the correction may cause the accuracy of the angle clock, contributing to the reduction in the engine control accuracy for the engine control unit.
  • an object of at least one aspect of the present invention is to provide engine control apparatuses, which are capable of generating an operation clock having an accuracy higher than that of operation clocks to be generated by conventional engine control apparatuses.
  • an apparatus for controlling an engine includes an interval measuring unit configured to receive an input signal input thereto and composed of a regular region and an irregular region repetitively appearing in time.
  • the input signal has a level that regularly changes in time in a predetermined direction in the regular region thereof every amount of regular operation of the engine.
  • the level of the input signal irregularly changes in time in the predetermined direction in the irregular region thereof with an amount of irregular operation of the engine.
  • the interval measuring unit is configured to sequentially measure an interval between appearance of a predetermined-directed level change in the input signal and that of a temporally next predetermined-directed level change therein.
  • the apparatus includes a multiplication clock generating unit configured to sequentially use one of the measured intervals as a reference interval and to divide, by a multiplication number, the reference interval so as to generate a multiplication clock, the multiplication clock including a train of clock pulses whose clock cycle corresponds to a division of the reference interval by the multiplication number.
  • the apparatus includes an engine control unit configured to control the engine in synchronization with the multiplication clock generated by the multiplication clock generating unit.
  • the apparatus includes an irregular-region start detector configured to detect that a predetermined-directed level change in the input signal is synchronized with a start of appearance of the irregular region thereof.
  • the apparatus includes an irregular-region end detector configured to detect that a predetermined-directed level change in the input signal is synchronized with an end of the irregular region thereof.
  • the apparatus includes a fixing unit configured to fix the reference interval to a predetermined value when it is detected that the predetermined-directed level change in the input signal is synchronized with the start of appearance of the irregular region thereof.
  • the apparatus includes a resetting unit configured to reset the reference interval from the predetermined-value to one of the measured intervals when it is detected that the predetermined-directed level change in the input signal is synchronized with the end of the irregular region thereof.
  • a program product embedded in a media accessible by a computer for controlling an engine.
  • the program product includes an interval measuring for instructing a computer to receive an input signal input thereto and composed of a regular region and an irregular region repetitively appearing in time.
  • the input signal has a level that regularly changes in time in a predetermined direction in the regular region thereof every amount of regular operation of the engine.
  • the level irregularly changes in time in the predetermined direction in the irregular region thereof with an amount of irregular operation of the engine.
  • the interval measuring means is configured to instruct a computer to sequentially measure an interval between appearance of a predetermined-directed level change in the input signal and that of a temporally next predetermined-directed level change therein.
  • the program product includes a multiplication clock generating means for instructing a computer to sequentially use one of the measured intervals as a reference interval and to divide, by a multiplication number, the reference interval so as to generate a multiplication clock.
  • the multiplication clock includes a train of clock pulses whose clock cycle corresponds to a division of the reference interval by the multiplication number.
  • the program product includes an engine control means for instructing a computer to control the engine in synchronization with the multiplication clock generated by the multiplication clock generating means.
  • the program product includes an irregular-region start detecting means for instructing a computer to detect that a predetermined-directed level change in the input signal is synchronized with a start of appearance of the irregular region thereof.
  • the program product includes an irregular-region end detecting means for instructing a computer to detect that a predetermined-directed level change in the input signal is synchronized with an end of the irregular region thereof.
  • the program product includes a fixing means for instructing a computer to fix the reference interval to a predetermined value when it is detected that the predetermined-directed level change in the input signal is synchronized with the start of appearance of the irregular region thereof.
  • the program product includes a resetting means for instructing a computer to reset the reference interval from the predetermined-value to one of the measured intervals when it is detected that the predetermined-directed level change in the input signal is synchronized with the end of the irregular region thereof.
  • FIG. 1 is a block diagram schematically illustrating an example of the structure of an electronic control unit installed in a vehicle according to an embodiment of the present invention
  • FIG. 2 is a signal waveform chart schematically illustrating a crank signal, first and second cam signals, and a cam-edge signal according to the embodiment of the present invention
  • FIG. 3 is a block diagram schematically illustrating an example of the structure of an angle clock generating unit illustrated in FIG. 1 ;
  • FIG. 4 is a time chart schematically illustrating variations of parameters of an angle clock generating unit with variation of an input signal according to the embodiment of the invention
  • FIG. 5 is a flowchart schematically illustrating an input signal diagnosing task to be executed by a CPU illustrated in FIG. 1 ;
  • FIG. 6 is a flowchart schematically illustrating a time-synchronized task to be executed by the CPU illustrated in FIG. 1 ;
  • FIG. 7 is a flowchart schematically illustrating a crank-edge interrupt task to be executed by the CPU illustrated in FIG. 1 ;
  • FIG. 8 is a time chart schematically illustrating variations of parameters of the angle clock generating unit with variation of the input signal during the crank-edge interrupt task illustrated in FIG. 7 ;
  • FIG. 9 is a time chart schematically illustrating variations of parameters of the angle clock generating unit with variation of the input signal during the crank-edge interrupt task illustrated in FIG. 7 ;
  • FIG. 10 is a flowchart schematically illustrating a cam-edge interrupt task to be executed by the CPU illustrated in FIG. 1 ;
  • FIG. 11 is a table schematically illustrating correspondences between individual initial values of respective counters of angle clock module illustrated in FIG. 3 and individual active edges in the cam-edge signal in a table format according to the embodiment;
  • FIG. 12 is a time chart schematically illustrating variations of parameters of the angle clock generating unit with variation of the input signal during the cam-edge interrupt task illustrated in FIG. 11 ;
  • FIG. 13 is a time chart schematically illustrating variations of parameters of the angle clock generating unit with variation of the crank signal when a correction in step S 412 of FIG. 7 is carried out;
  • FIG. 14 is a time chart schematically illustrating variations of parameters of the angle clock generating unit with variation of the crank signal when corrections in steps S 612 and S 622 of FIG. 10 are carried out.
  • ECU electronice control unit
  • the ECU 1 serves as an engine control unit operative to control a four-cycle internal combustion engine E installed in a vehicle and having, for example, the first (# 1 ) to sixth (# 6 ) cylinders.
  • FIG. 1 is a block diagram illustrating an example of the structure of the ECU 1 , which is installed in advance in the vehicle according to the embodiment of the present invention.
  • the ECU 1 according to the embodiment is provided with an input circuit 10 , an output circuit 20 , and a microcomputer 30 .
  • the input and output circuits 10 and 20 are electrically connected to the microcomputer 30 .
  • the input circuit 10 is electrically connected to a crankshaft sensor 11 , a first camshaft sensor 12 , a second camshaft sensor 13 , and other sensors.
  • the crankshaft sensor 11 for example includes a reluctor disc 11 a having a plurality of teeth 11 b substantially spaced at angle intervals of, for example, 6 degrees around the periphery of the disc 11 a .
  • the reluctor disc 11 a is coaxially mounted on a crankshaft CS serving as the engine's main shaft for delivering rotary motion taken from the reciprocating pistons and rods of the cylinders.
  • the reluctor disc 11 a has, for example, a tooth-missing portion 11 c composed of, for example, k adjacent teeth missing.
  • the crankshaft sensor 11 for example includes a pickup 11 d operative to, for example, magnetically detect the teeth 11 b of the reluctor disc 11 a on the crankshaft CS as it rotates to generate a crank signal based on the detected result.
  • the crank signal is input to the input circuit 10 .
  • the rotational region of the crankshaft CS when the rotational position of the crankshaft CS reaches within a given rotational region so that the tooth-missing portion 11 c is located in front of the pickup 11 d to be detectable thereby, the rotational region of the crankshaft CS will be referred to as “specified region” hereinafter.
  • crankshaft CS reaches the specified region every crank angle of 360 degrees. In other words, the crankshaft CS reaches the specified region twice per one engine cycle (the crank angle of 720 degrees).
  • the first camshaft sensor 12 is operative to, for example, magnetically detect rotational positions of a first camshaft CM 1 as it rotates, for example, at one-half rotational speed of the crankshaft CS to generate a first cam signal based on the detected result.
  • the first cam signal is input to the input circuit 10 .
  • the second camshaft sensor 13 is operative to, for example, magnetically detect rotational positions of a second camshaft CM 2 as it rotates, for example, at one-half rotational speed of the crankshaft CS to generate a second cam signal based on the detected result.
  • the second cam signal is input to the input circuit 10 .
  • first and second camshafts CM 1 and CM 2 are configured to be driven by gears, belts, and/or a chain from the crankshaft CS, and contain a series of cams for opening and closing the intake and exhaust valves, respectively.
  • the crank signal is configured to have a level repetitively varying in time like pulses with rotation of the crankshaft CS.
  • the first cam signal is configured to have a level repetitively varying in time like pulses with rotation of the first camshaft CM 1
  • the second cam signal is configured to have a level repetitively varying in time like pulses with rotation of the second camshaft CM 2 .
  • crank signal and the first and second cam signals will be described in detail hereinafter with reference to FIG. 2 .
  • the level of the crank signal changes in a predetermined same direction in a pulse every time the crank shaft CS (the reluctor disc 11 a ) rotates at a unit angle ⁇ degrees crank angle (CA) while the rotational position of the crankshaft CS is not located within the specified region.
  • the predetermined same direction is set to a high-to-low direction
  • the unit angle ⁇ degrees crank angle is set to 6 degrees crank angle.
  • a rotational angle of the crankshaft CS that allows the level of the crank signal to change in the same direction (high-to-low direction) in a pulse is k-times greater than the unit angle ⁇ .
  • k is set to 3.
  • crankshaft CS While the rotational position of the crankshaft CS is located within a region except for the specified region, a same-directed active edge, such as a trailing edge, of the transient level change of the crank signal in a pulse appears every time the crankshaft CS rotates at the unit angle ⁇ .
  • crankshaft CS While the rotational position of the crankshaft CS is located within the specified region, same-directed k-1 active edges of the transient level change of the crank signal do not appear even though the crankshaft CS continuously rotates every unit angle ⁇ .
  • active edges same-directed active edges, such as trailing edges or rising edges, appearing in a signal whose level transiently repetitively changes in time like a pulse signal will be referred to merely as “active edges” hereinafter.
  • the normal time interval is an interval between temporally adjacent active edges of the crank signal while the rotational position of the crankshaft CS is located within a region except for the specified region.
  • a portion (region) of the crank signal corresponding to the specified region in other words, the k-times time interval between temporally adjacent active edges of the crank signal as compared with the normal time interval will be referred to as a pulse-missing portion (irregular region) M hereinafter.
  • the pulse-missing portion M also appears, in the crank signal, once every crank angle of 360 degrees.
  • an active edge appearing every time the crankshaft CS rotates at a predetermined crank angle of, for example, 120 degrees CA corresponds to TDC (Top Dead Center) of each of the individual cylinders # 1 , # 5 , # 3 , # 6 , # 2 , and # 4 in this order in FIG. 2 .
  • the predetermined crank angle of 120 degrees can be set by dividing the crank angle of 720 degrees corresponding to one engine cycle by the number of cylinders, such as 6.
  • a reference position of the crank signal is set to correspond to an active edge a predetermined crank angle of, for example 18 degrees before the active edge corresponding to the TDC of the first cylinder # 1 .
  • the reference position of the crank signal is illustrated by “0” in FIG. 2 .
  • the pulse-missing portion M appears, in the crank signal, once every crank angle of 360 degrees.
  • the pulse-missing portions M are divided into first pulse-missing portions M 1 and second pulse-missing portions M 2 .
  • the first pulse-missing portion M 1 starts from a first active edge the crank angle of 108 degrees after the active edge appearing at the reference position every engine cycle.
  • the second pulse-missing portion M 2 starts from a second active edge the crank angle of 360 degrees after the first active edge every engine cycle.
  • the k-times time interval as compared with the normal time interval after the first active edge corresponds to the first pulse-missing portion M 1
  • the k-times time interval as compared with the normal time interval after the second active edge corresponds to the second pulse-missing portion M 2 .
  • the first cam signal is configured to:
  • the second cam signal is configured to:
  • crank angle of 720 degrees the series of variations every engine cycle (crank angle of 720 degrees).
  • the other sensors are installed beforehand in the vehicle and arranged to measure various types of physical quantities. These physical quantities are required for the ECU 1 to control the individual control targets. Measurement signals indicative of measurands output from the other sensors are periodically input to the input circuit 10 .
  • the input circuit 10 serves as a waveform shaping circuit. Specifically, the input circuit 10 is operative to apply waveform shaping to the crank signal, the first and second cam signals, and the measurement signals respectively output from the crankshaft sensor 11 , the first and second cam sensors 12 and 13 , and the other sensors. In addition, the input circuit 10 is operative to output the waveform-shaped signals to the microcomputer 30 .
  • the output circuit 20 is operative to activate control targets associated with engine control, such as actuators including injectors and igniters for the respective cylinders, based on target-control instructions (event instructions) sent from the microcomputer 30 .
  • control targets associated with engine control such as actuators including injectors and igniters for the respective cylinders, based on target-control instructions (event instructions) sent from the microcomputer 30 .
  • the microcomputer 30 consists essentially of a CPU 100 , an angle clock generating unit 200 , a timer output unit 300 , a flash ROM 400 , and a RAM 500 , these units 200 , 300 , and 400 are electrically connected to the CPU 100 .
  • the CPU 100 is operative to control over-all operations of the microcomputer 30 .
  • the angle clock generating unit 200 is operative to receive the crank signal and the first and second cam signals output from the input circuit 10 so as to generate an angle clock described hereinafter.
  • the timer output unit 300 is operative to output event instructions in synchronization with the clock cycle of the angle clock generated by the angle clock generating unit 200 on the basis of instructions sent from the CPU 100 .
  • the flash ROM 400 is used as an example of various types of nonvolatile memories. Specifically, the flash ROM 400 has stored therein a plurality of programs. At least one of the programs causes the CPU 100 to execute various tasks including: (1) an input signal diagnosing task, (2) time-synchronized task, (3) crank-edge interrupt task, and (4) cam-edge interrupt task, which will be described hereinafter.
  • the RAM 500 is operative to be quickly accessible by the CPU 100 and to store therein data processed by the CPU 100 .
  • the angle clock generating unit 200 includes an input selecting module 210 , an edge interval measuring module 220 , a reference time selecting module 230 , a multiplication clock generating module 240 , a pass-angle interrupt module 250 , and an angle clock module 260 .
  • Each of the modules 210 , 220 , 230 , 240 , and 250 is operatively connected to the CPU 100 .
  • the input selecting module 210 is operatively connected to the edge interval measuring module 220 , the multiplication clock generating module 240 , the pass-angle interrupt module 250 , and the angle clock module 260 .
  • the input selecting module 210 is configured to receive the crank signal and the first and second cam signals sent from the input circuit 10 .
  • the input selecting module 210 is also configured to generate a cam-edge signal based on the received first and second cam signals, select one of the received crank signal and the cam-edge signal, and output the selected one of the crank signal and the cam-edge signal to at least one of the modules 220 , 230 , 240 , 250 , and 260 based on instructions sent from the CPU 100 .
  • the cam-edge signal is configured to have a level transiently vary in time in a predetermined same direction, such as a low-to-high direction, each time a level-variation appears in the individual first and second cam signals.
  • a same-directed active edge such as a rising edge
  • Same-directed active edges of the cam-edge signal will be referred to merely as “active edges” hereinafter.
  • the level of the cam-edge signal is configured to transiently change in time in the low-to-high direction at individual change points P and Q corresponding to the individual level-variation timings of the first and second cam signals.
  • the cam-edge signal regularly changes in level at a change point P each time one of the first and second cam shafts CM 1 and CM 2 is rotated by a regular angel of 120 degrees CA.
  • the cam-edge signal irregularly changes in level at a change point Q each time one of the first and second cam shafts CM 1 and CM 2 is rotated by a 90 degrees CA after some of the change points P.
  • the cam-edge signal consists of regular regions in which the change points P only appear and irregular regions in which the change points Q appear.
  • the input-selecting module 210 can be designed to logically OR the first and second cam signals to generate the cam-edge signal.
  • the input selecting module 210 is further configured to directly output, to the CPU 100 , the received crank signal and first and second cam signals.
  • the edge interval measuring module 220 is operatively connected to the reference time selecting module 230 , and includes an edge interval measuring counter 220 a.
  • the edge interval measuring counter 220 a works to measure a time interval between the current active edge and the next active edge temporally adjacent thereto appearing in the input signal.
  • the edge interval measuring counter 220 a works to:
  • the system clock allows synchronization of the tasks in the microcomputer 100 with each other.
  • the system clock consists of a repetitive series of the clock pulses with a constant clock cycle and a constant clock frequency; this clock frequency is higher than a frequency of active edges in the input signal.
  • the variation of the count value of the edge interval-measuring counter 220 a is schematically illustrated by T 0 to T 6 at “EDGE INTERVAL MEASURING COUNTER” in FIG. 4 .
  • the edge interval measuring module 220 is also operative to pass a count value (measured time interval) of the edge interval measuring counter 220 a to the reference time selecting module 230 each time a next active edge currently appears in the input signal before reset of the count value.
  • the reference time selecting module 230 is operatively connected to the multiplication clock generating module 240 , and includes a register 230 a.
  • the reference time selecting module 230 is operative to:
  • the measured edge-to-edge interval is selected as the multiplication-clock reference time (see “EDGE-TO-EDGE INTERVAL” illustrated at “REFERENCE TIME SELECTION” in FIG. 4 ).
  • the multiplication clock generating module 240 is operatively connected to the pass-angle measuring module 250 and the angle clock module 260 , and includes first and second registers 240 a and 240 b .
  • the second register 240 b is operative to store therein a multiplication number f.
  • a default of the multiplication number f is set to 60 for the crank signal, and the multiplication number f for the crank signal whose default is “60” will be specifically expressed by “f 1 ” hereinafter.
  • the multiplication clock generating module 240 works to:
  • the multiplication-clock reference time depends on the count value of the edge interval measuring counter 220 a depending on a corresponding interval of temporally adjacent active edges in the input signal. For this reason, the clock cycle of the multiplication clock depends on change of the multiplication-clock reference time.
  • the cycle of the multiplication clock is set to T 0 /f.
  • the count value T 0 stored in the first register 240 a is updated to a count value T 1 , the cycle of the multiplication clock signal is changed from T 0 /f to T 1 /f.
  • the pass-angle measuring module 250 incorporates a pass-angle measuring counter 250 a for counting up the number of variations in the multiplication clock in a predetermined same direction, such as a low-to-high direction in the embodiment.
  • the pass-angle measuring counter 250 a works to:
  • the input signal to be input from the input selecting module 210 to the pass-angle interrupt module 250 is any one of the crank signal and the cam-edge signal.
  • the crank signal is configured to have a level transiently varying repetitively in time with rotation of the crankshaft CS
  • the cam-edge signal is configured to have a level transiently varying repetitively in time in a predetermined same direction, such as a low-to-high direction, with rotation of any one of the first and second camshafts CM 1 and CM 2 .
  • the multiplication clock has a clock cycle that is an integral submultiple of a corresponding time interval between temporally adjacent active edges in the input signal (any one of the crank signal and the cam-edge signal).
  • the pass-angle measuring counter 250 a is operative to measure a rotational angle of the crankshaft CS between each temporally adjacent active edges in the input signal with a high resolution as compared with that as in the case of measuring the rotational angle in synchronization with an active edge of the input signal.
  • the pass-angle measuring counter 250 a is operative to measure a rotational angle of the crankshaft CS passing from 0 degrees crank angle to ⁇ degrees crank angle between each temporally adjacent active edges in the input signal with a resolution f-times greater than that as in the case of measuring the rotational angle in synchronization with an active edge of the input signal.
  • the pass-angle measuring module 250 includes a threshold register 250 b for storing a threshold value for the count value of the pass-angle measuring counter 250 a .
  • the pass-angle measuring module 250 is operative to generate an interrupt when the count value of the pass-angle measuring counter 250 a is equal to or greater than the threshold value stored in the threshold register 250 b , thereby outputting the interrupt to the CPU 100 .
  • a default of the threshold value is set to a predetermined value greater than a reference count value that the pass-angle measuring counter 250 a can reach while no pulse-missing portions M appear in the crank signal; this reference count value corresponds to ⁇ degrees crank angle of the crankshaft CS.
  • the default of the threshold value is also set to be smaller than a specified count value that the pass-angle measuring counter 47 a can reach while one of the pulse-missing portions M appears in the crank signal.
  • the threshold register 47 b As the default of the threshold value, a value 2.5 times as great as the reference count value ⁇ is stored in the threshold register 47 b ; this default of the threshold is given by 2.5 ⁇ .
  • the angle clock module 260 includes a reference counter 260 a , a guard counter 260 b , and an angular counter 260 c.
  • the reference counter 260 a is operative to count up the number of variations in the multiplication clock in the predetermined same direction, such as the low-to-high direction, in the embodiment.
  • the guard counter 260 b is operative to count up by the multiplication number f each time the level of the input signal input thereto from the input selecting module 210 varies in the predetermined direction, such as the low-to-high direction.
  • the angular counter 260 c is operative to cause its count value to automatically follow the count value of the reference counter 260 a in synchronization with an active edge, for example, rising edge of each clock pulse of the system clock.
  • the angle clock module 260 also includes first and second registers (REG) 260 d and 260 e .
  • the first register 260 d is operative to store therein an upper limit for the reference counter 260 a and the angular counter 260 c ; this upper limit can be set by instructions sent from the CPU 100 .
  • the second register 260 e is operative to store therein a mode value. The mode value determines the operation mode of the reference counter 260 a.
  • the reference counter 260 a is configured to:
  • the reference counter 260 a is also configured to execute the counting operation in one of the operation modes; this one of the operation modes is determined by the mode value stored in the second register 260 e.
  • the operation modes include:
  • the count values of the angular counter 260 c are individually passed to the timer output unit 300 as clock pulses of an angle clock.
  • the timer output unit 300 is operative to receive the angle clock, and to output, to the output circuit 20 , an event instruction synchronized with each clock pulse of the angle clock.
  • the output circuit 20 When receiving an event instruction sent from the timer output unit 300 , the output circuit 20 is operative to activate at least one of the actuators, such as injectors and/or igniters for the respective cylinders, based on the received event instruction sent from the timer output unit 300 .
  • the actuators such as injectors and/or igniters for the respective cylinders
  • actuator's operation control such as ignition control and fuel-injection control, in synchronization with rotation of the crankshaft CS with high resolution.
  • the count values of the reference counter 260 a can be individually passed to the timer output unit 300 as clock pulses of an angle clock.
  • the microcomputer 30 includes a non-edge period measuring counter 30 a with an initial count value of zero for measuring a non-edge period in the crank signal.
  • the counter 30 a can be installed as a hardware component or a software component in the microcomputer 30 .
  • the CPU 100 determines whether an engine speed of the vehicle is equal to or greater than a predetermined value Na. If it is determined that the engine speed is less than the predetermined value Na (the determination in step S 110 is NO), the microcomputer 13 exits the input-signal diagnosing task.
  • the engine speed can be calculated by predetermined engine speed calculating operations using the crank signal.
  • the CPU 100 measures the time interval of the crank angle of 360 degrees corresponding to the occurrence cycle of the pulse-missing portions M, and calculates the engine speed based on the measured time interval.
  • the pulse-missing portions M can be detected in, for example, the following manner. Specifically, intervals between temporally adjacent active edges of the crank signal are measured, and when a current measured interval is equal to or greater than the product of a previous measured interval and a predetermined pulse-missing detecting ratio of, for example, 2, it is determined that the current measured interval corresponds to one of the pulse missing portions M.
  • the predetermined value Na represents a threshold engine speed allowing a time interval between temporally adjacent trailing edges of the normal crank signal to be sufficiently smaller than the regular interval Tc.
  • step S 110 can prevent the normal crank signal from being erroneously determined as abnormal.
  • step S 110 the CPU 100 proceeds to step S 120 .
  • step S 120 the CPU 100 determines whether an active edge, such as a trailing edge, appears in the crank signal during the passage of the regular time interval Tc from the previous input-signal diagnosing task to this current input-signal diagnosing task.
  • the CPU 100 stores in, for example, the RAM 500 information representing that the crank signal is normal as the diagnosed result in step S 130 .
  • the CPU 100 clears the count value of the non-edge period measuring counter 30 a in step S 140 , exiting the input-signal diagnosing task.
  • the non-edge period measuring counter 30 a is configured to be reset each time the microcomputer 30 is booted.
  • the non-edge period measuring counter 30 a serves as a counter designed to add up the number of times where it is determined that no rising edges appear in the crank signal in the following operations of the input-signal diagnosing task.
  • the CPU 100 checks whether the count value of the non-edge period measuring counter 30 a exceeds a predetermined value Nb of, for example, 10 in step S 150 .
  • the CPU 100 increments the count value of the non-edge period measuring counter 30 a by 1, exiting the input-signal diagnosing task.
  • the CPU 100 a stores in, for example, the RAM 500 , information representing that the crank signal is abnormal as the diagnosed result in step S 170 , exiting the input-signal diagnosing task.
  • the engine speed is equal to or greater than the predetermined value Na (the determination in step S 110 is YES).
  • the crank signal is determined to be abnormal (see step S 170 ).
  • the predetermined period of time is represented as the product of the regular time interval Tc and the predetermined value Nb (Tc ⁇ Nb), and that an active trailing edge is supposed to appear in the crank signal during the passage of the predetermined period of time.
  • the CPU 100 carries out the input-signal diagnosing task illustrated in FIG. 5 for the first and second cam signals as in the case of the crank signal (see FIG. 5 ), thereby determining whether the first and second cam signals are normal. Because the instructions of the input-signal diagnosing task for the first and second cam signals are substantially identical to those for the crank signal, the descriptions of the instructions are omitted.
  • the CPU 100 When launching the time-synchronized task program, the CPU 100 refers to the information stored in the RAM 500 and representing the diagnosed result for the crank signal (see steps S 130 and S 170 in FIG. 5 ), thereby determining whether the crank signal is abnormal based on the referred result in step S 210 .
  • step S 210 the CPU 100 sends, to the input selecting module 210 , a crank-signal selection instruction to select the crank signal as the input signal.
  • step S 220 the CPU 100 sends, to each of the modules 220 , 230 , 240 , 250 , and 260 , the crank-signal selection instruction. Thereafter, the CPU 100 exits the time-synchronized task.
  • the crank-signal selection instruction received by the input selecting module 210 allows the module 210 to select the crank signal as the input signal, thereby passing the selected crank signal as the input signal to each of the modules 220 , 230 , 240 , 250 , and 260 .
  • the crank-signal selection instruction received by the multiplication clock generating module 240 allows the module 240 to store, as the multiplication number f 1 , 60 for the crank signal in the second register 240 b.
  • the crank-signal selection instruction received by the angle clock module 260 allows the module 260 to store, in the first register 260 d , an upper limit of each of the reference counter 260 a and the angular counter 260 c ; this upper limit is determined for the crank signal.
  • step S 210 determines whether the crank signal is abnormal. If it is determined that the crank signal is abnormal (the determination in step S 210 is YES), the CPU 100 proceeds to step S 230 .
  • step S 230 the CPU 100 refers to the information stored in the RAM 500 and representing the diagnosed result for each of the first and second cam signals to determine whether at least one of the first and second cam signals is abnormal based on the referring result.
  • step S 230 the CPU 100 sends, to the input selecting module 210 , a cam-edge signal selection instruction to select the cam-edge signal as the input signal.
  • step S 240 the CPU 100 sends, to each of the modules 220 , 230 , 240 , 250 , and 260 , the cam-edge signal selection instruction. Thereafter, the CPU 100 exits the time-synchronized task.
  • the cam-edge signal selection instruction received by the input selecting module 210 allows the module 210 to select the cam-edge signal as the input signal, thereby passing the selected cam-edge signal as the input signal to each of the modules 220 , 230 , 240 , 250 , and 260 .
  • the cam-edge signal selection instruction received by the multiplication clock generating module 240 allows the module 240 to store, as the multiplication number f, a value for the cam-edge signal in the second register 240 b .
  • the multiplication number f for the cam-edge signal will be specifically expressed by “f 2 ” hereinafter.
  • the value as the multiplication number f 2 for the cam-edge signal stored in the second register 240 b is obtained by:
  • the cam-edge signal selection instruction received by the angle clock module 260 allows the module 260 to store, in the first register 260 d , an upper limit of each of the reference counter 260 a and the angular counter 260 c ; this upper limit is determined for the cam-edge signal.
  • step S 230 the CPU 100 exits the time-synchronized task.
  • crank-edge interrupt task program Third, instructions of a crank-edge interrupt task program will be described hereinafter with reference to FIG. 7 .
  • the instructions allow the CPU 100 to execute the crank-edge interrupt task each time an active edge appears in the crank signal output from the input selecting module 210 as the input signal (see step S 220 in FIG. 6 ) after the microcomputer 30 is booted,
  • the CPU 100 determines whether the trigger active edge represents the end of a pulse-missing portion Ma in the crank signal in step S 310
  • temporally adjacent active edges E 1 and E 2 in the crank signal constitute a pulse-missing portion Ma therein.
  • the time interval of the pulse-missing portion Ma between the active edges E 1 and E 2 corresponds to a measured count value T 1 of the edge interval measuring counter 220 a .
  • Intervals between temporally adjacent active edges of other portions except for the pulse-missing portions M in the crank signal respectively correspond to measured count values T 0 , T 2 , T 3 , T 4 , . . . .
  • the time interval of the pulse-missing portion Ma in the crank signal is longer than the intervals of the other portions except for the pulse-missing portions M therein. For this reason, the count value T 1 corresponding to the time interval of the pulse-missing portion Ma in the crank signal is greater than the other count values each corresponding to one of the other portions therein.
  • a measured value (count value) of the pass-angle measuring counter 250 a depends on a corresponding time interval between temporally adjacent same-directed edges in the crank signal. For this reason, a count value of the pass-angle measuring counter 250 a corresponding to the time interval of the pulse-missing portion Ma in the crank signal is greater than that of the counter 250 a corresponding to another time interval of another portion in the crank signal except for the pulse-missing portions M.
  • the count value of the pass-angle measuring counter 250 a corresponding to the time interval of the pulse-missing portion Ma in the crank signal exceeds the default ( ⁇ 2.5) of the threshold value stored in the threshold register 250 b .
  • the count value of the pass-angle measuring counter 250 a corresponding to the time interval of the pulse-missing portion Ma in the crank signal is illustrated by “ ⁇ 3” in FIG. 8 .
  • the pass-angle measuring module 250 when the count value of the pass-angle measuring counter 250 a corresponding to the time interval of the pulse-missing portion Ma in the crank signal reaches the default of the threshold value, the pass-angle measuring module 250 generates an interrupt, thereby outputting it to the CPU 100 .
  • the CPU 100 determines that the trigger active edge represents the end of a pulse-missing portion M in the crank signal (the determination in step S 310 is YES).
  • an active edge E 2 is the trigger active edge representing the end of a pulse-missing portion Ma.
  • the CPU 100 determines whether a crank-position determining flag F 1 holds information indicative of OFF in step S 320 .
  • the crank-position determining flag F 1 is for example set by software in the microcomputer 30 each time the microcomputer 30 is booted.
  • the information indicative of OFF is set as default information of the crank-position determining flag F 1 during the microcomputer's start-up process.
  • step S 320 If it is determined that the crank-position determining flag F 1 holds the information indicative of the default of OFF (the determination in step S 320 is YES), the CPU 100 determines a timing immediately after microcomputer startup, proceeding to step S 330 .
  • step S 330 the CPU 100 sets the product of “59” and the multiplication number f 1 , which is set to 60 in the crank-edge interrupt task, to the count value of the reference counter 260 a .
  • step 340 the CPU 100 sets the product of “59” and the multiplication number f 1 , which is set to 60 in the crank-edge interrupt task, to the count value of the angle counter 260 c.
  • the product of “59” and the multiplication number f 1 (60) to be set to the count value of the reference counter 260 a allows the count value thereof to be cleared (zero) when the next active edge E 3 appears in the crank signal.
  • the product of “59” and the multiplication number f 1 (60) to be set to the count value of the angular counter 260 c allows the count value thereof to be cleared (zero) upon an appearance of the next active edge E 3 in the crank signal.
  • the CPU 100 changes the information held by the crank-position determining flag F 1 from OFF to ON in step S 350 .
  • the CPU 100 After the completion of the execution of the instruction in step S 350 , or a negative determination representing that the crank-position determining flag F 1 does not hold the information indicative of OFF in step S 320 , the CPU 100 sets “0” to the count value of the guard counter 260 b in step S 360 .
  • the count value of zero (0) set to the guard counter 260 b represents a count value that each of the reference counter 260 a and the angular counter 260 c should take when the next active edge E 3 appears in the crank signal.
  • the guard counter 260 b is configured such that its count value at a timing of an appearance of an active edge in the crank signal represents a value that each of the reference counter 260 a and the angular counter 260 c should take at a timing of an appearance of the next active edge in the crank signal. This permits the count value of each of the reference counter 260 a and the angular counter 260 c to be guarded even if the engine suddenly accelerates or decelerates.
  • step S 360 the CPU 100 sends, to the angle clock module 260 , an instruction indicative of the enabling mode in step S 370 .
  • the instruction indicative of the enabling mode and received by the angle clock module 260 allows the module 260 to store, as the mode value, an enabling mode value indicative of the enabling mode in the second register 260 e .
  • the enabling mode value stored in the second register 260 e permits the reference counter 260 a to count in the enabling mode described above even if “0” is set to the count value of the guard counter 260 b.
  • the CPU 100 sends, to the reference time selecting module 230 , an instruction to select, as the multiplication-clock reference time, the edge-to-edge interval in step S 372 .
  • the reference time selecting module 230 transfers, to the multiplication clock generating module 240 , the edge-to-edge interval passed from the edge interval measuring module 220 until an instruction to select, as the multiplication-clock reference time, the fixed time is passed thereto from the CPU 100 (see step S 414 hereinafter).
  • the CPU 100 sends, to the multiplication clock generating module 240 , an instruction to correct a multiplication-clock reference time stored in the first register 240 a in step S 380 . Thereafter, the CPU 100 exits the crank-edge interrupt task.
  • the instruction is to set, as the multiplication-clock reference time to be stored in the first register 240 a , a value calculated by dividing the edge-to-edge interval passed from the reference time selecting module 230 by a predetermined value.
  • the multiplication clock generating module 240 works to:
  • the count value corresponding to a time interval, such as a T 2 , of a pulse-missing portion Ma in the crank signal is k-times as much as that corresponding to a time interval, such as a T 1 , of one of the other portions except for the pulse-missing portion Ma therein.
  • the width of the time interval “T 1 ” longer than that of the time interval “T 2 ”, which is illustrated as “EDGE INTERVAL” in FIG. 8 is independent of the length of the time interval “T 1 ”.
  • the length of the time interval “T 2 ” is longer than that of the time interval “T 1 ” in FIG. 8 .
  • the predetermined value is set to k representing a ratio of a time interval between temporally adjacent active edges of a pulse-missing portion M in the crank signal to that between temporally adjacent active edges of another portion therein; this k is set to 3.
  • the CPU 100 determines whether the trigger active edge represents the head of a pulse-missing portion M in step S 400 .
  • the CPU 100 executes the determination in step S 400 by, for example, determining whether the count value of the angular counter 260 c represents a rotational position of the crankshaft CS corresponding to the head of a teeth-missing portion 11 c . If it is determined that the count value of the angular counter 260 c represents the rotational position of the crankshaft CS corresponding to the head of a teeth-missing portion 11 c , the CPU 100 determines that the trigger active edge for the crank-edge interrupt task represents the head of a pulse-missing portion M in step S 400 .
  • the CPU 100 sets the product of “59” and the multiplication number f 1 , which is set to 60 in the crank-edge interrupt task, to the count value of the guard counter 260 b in step S 410 .
  • the CPU 100 sends, to the reference time selecting module 230 , an instruction to store, in the register 230 a , the edge-to-edge interval as the fixed time in step S 412 ; this edge-to-edge interval is passed from the edge interval measuring module 220 in response to the trigger active edge for the crank-edge interrupt task.
  • the reference time selecting module 230 stores, in the register 230 a , the edge-to-edge interval as the fixed time.
  • the CPU 100 sends, to the reference time selecting module 230 , an instruction to select, as the multiplication-clock reference time, the fixed time in step S 414 .
  • the reference time selecting module 230 transfers, to the multiplication clock generating module 240 , the fixed time stored in the register 230 a until an instruction to select, as the multiplication-clock reference time, the edge-to-edge interval is passed thereto from the CPU 100 (see step S 372 set forth above).
  • step S 414 After the completion of the execution of the instruction in step S 414 , or a negative determination in step S 400 , the CPU 100 sends, to the angle clock module 260 , an instruction indicative of the disabling mode in step S 420 . Thereafter, the CPU 100 exits the crank-edge interrupt task.
  • the instruction indicative of the disabling mode and received by the angle clock module 260 allows the module 260 to store, as the mode value, a disabling mode value indicative of the disabling mode in the second register 260 e .
  • the disabling mode value stored in the second register 260 e permits the reference counter 260 a to count in the disabling mode described above. Specifically, in the disabling mode, the reference counter 260 a counts up until its count value reaches the count value of the guard counter 260 b.
  • step S 310 and S 400 are respective negative, so that execution of the CPU 100 is shifted to step S 420 , and after completion of the operation in step S 420 , the crank-edge interrupt task is terminated.
  • step S 310 , S 400 , and S 420 are repeatedly executed by the CPU 100 in this order each time an active edge appears in the crank signal (see a section e 1 in FIG. 8 ).
  • the count value of the pass-angle measuring counter 250 a exceeds the threshold value stored in the threshold register 250 b before an active edge E 2 appearing in the crank signal represents the end of a pulse-missing portion M (see in FIG. 8 ).
  • the determination in step S 400 is negative.
  • the excess of the count value of the pass-angle measuring counter 250 a exceeds the threshold value over the threshold value allows the pass-angle measuring module 250 to generate an interrupt, and to output it to the CPU 100 .
  • the interrupt is received by the CPU 100 so that, when the active edge E 2 appears in the crank signal after receipt of the interrupt, it is determined that the active edge E 2 represents the end of a pulse-missing portion M in the crank signal (the determination in step S 310 is YES).
  • execution of the CPU 100 is shifted to step S 320 and later.
  • step S 320 is affirmative, so that execution of the CPU 100 is shifted to steps S 330 and S 340 .
  • step S 330 the count value of the reference counter 260 a is set to the product of “59” and the multiplication number f 1 (60), and the count value of the angular counter 260 c is set to the product of “59” and the multiplication number f 1 (60) in step S 340 . Thereafter, the crank-position determining flag F 1 is set to the information indicative of ON in step S 350 .
  • step S 360 the count value of the guard counter 260 b is set to “0”, and the reference counter 260 a executes the count-up operation in the enabling mode in step S 370 .
  • step S 360 Even if the count value of the guard counter 260 b is set to “0” in step S 360 , because the operating mode of the reference counter 260 a is set to the enabling mode in step S 370 , the reference counter 260 a continuously counts up until the count value reaches the upper limit stored in the first register 260 d (see a section e 3 in FIG. 8 ).
  • the edge-to-edge interval is selected as the multiplication-clock reference time in step S 372 , and the multiplication-clock reference time is corrected from T 2 to T 2 / 3 in step S 380 (see “T 2 / 3 ” in FIG. 8 ). Thereafter, the crank-edge interrupt task is terminated.
  • the multiplication clock generating module 240 generates, after the operation in step S 372 , the multiplication clock based on the edge-to-edge interval passed from the edge interval measuring module 220 until the fixed time is selected in step S 414 .
  • step S 310 , S 400 , and S 420 are repeatedly executed by the CPU 100 in this order each time an active edge appears in the crank signal.
  • the repeat execution of the instructions in step S 310 , S 400 , and S 420 is stopped at step S 400 when an active edge appearing in the crank signal represents the head of a pulse-missing portion M therein (see a section e 4 in FIG. 9 ).
  • the count value of the guard counter 260 b is set to the product of “59” and the multiplication number f 1 (60) in step S 410 .
  • the edge-to-edge interval is stored in the register 230 a of the reference time selecting module 230 as the fixed time in step S 412 . This allows the fixed time stored in the register 230 a to be selected as the multiplication-clock reference time (see a section e 5 and “FIXED TIME” at “REFERENCE TIME SELECTION” in FIG. 9 ).
  • the multiplication clock generating module 240 generates, after the operation in step S 414 , the multiplication clock based on the fixed time independently of the edge-to-edge interval measured by the edge interval measuring module 220 until the edge-to-edge interval is selected in step S 372 .
  • step S 310 determines that the active edge (E 26 ) represents the end of the pulse-missing portion (the determination in step S 310 is YES).
  • the crank-position determining flag F 1 is set to the information indicative of ON, the determination in step S 320 is NO, so that execution of the CPU 100 is shifted to step S 360 .
  • step S 360 the count value of the guard counter 260 b is set to “0”, end the reference counter 260 a continuously counts up with the count value of the guard counter 260 b unchanged until the count value of the reference counter 260 a is cleared (zero) (see a section e 6 in FIG. 9 ).
  • the multiplication clock generating module 240 generates, after the operation in step S 372 , the multiplication clock based on the edge-to-edge interval passed from the edge interval measuring module 220 until the fixed time is selected in step S 414 .
  • steps S 310 , S 400 , and S 420 are repeatedly executed by the CPU 100 until it is determined that an active edge appearing in the crank signal represents the head of a pulse-missing portion M (see a section e 7 in FIG. 9 ).
  • cam-edge interrupt task program Fourth, instructions of a cam-edge interrupt task program will be described hereinafter with reference to FIG. 10 .
  • the instructions allow the CPU 100 to execute the cam-edge interrupt task each time an active edge appears in the cam-edge signal output from the input selecting module 210 as the input signal (see step S 240 in FIG. 6 ) after the microcomputer 30 is booted.
  • the CPU 100 determines whether a cam-position determining flag F 2 holds information indicative of OFF in step S 510 .
  • the cam-position determining flag F 2 is for example set by software in the microcomputer 30 each time the microcomputer 30 is booted.
  • the information indicative of OFF is set as default information of the cam-position determining flag F 2 during the microcomputer's start-up process.
  • step S 510 If it is determined that the cam-position determining flag F 2 holds the information indicative of the default of OFF (the determination in step S 510 is YES), the CPU 100 determines a timing immediately after microcomputer startup, proceeding to step S 520 .
  • step S 520 If it is determined that the count value of the guard counter 260 b is equal to or greater than two-times the multiplication number f 2 (the determination in step S 520 is YES), the CPU 100 proceeds to step S 530 .
  • step S 530 the CPU 100 sets initial values to the respective count values of the reference counter 260 a , the guard counter 260 b , and the angular counter 260 c in step S 530 .
  • each active edge in the cam-edge signal corresponds to:
  • initial values to be stored in the reference counter 260 a are determined beforehand for the respective active edges in the cam-edge signal.
  • initial values to be stored in the guard counter 260 b are determined beforehand for the respective active edges in the cam-edge signal
  • initial values to be stored in the angular counter 260 c are determined beforehand for the respective active edges in the cam-edge signal.
  • FIG. 11 schematically illustrates correspondences between the individual initial values of the respective counters 260 a to 260 c and the individual active edges in the cam-edge signal in a table format.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “6000”, “0”, and “6000”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “3600”, “4800”, and “3600”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “5700”, “6900”, and “5700”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “1200”, “2400”, and “1200”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “2400”, “3600”, and “2400”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “0”, “1200”, and “0”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “2100”, “3300”, and “2100”.
  • the initial values of the counters 260 a , 260 b , and 260 c are respectively set to “4800”, “6000”, and “4800”.
  • data indicative of the correspondences between the individual initial values of the respective counters 260 a to 260 c and the individual active edges in the cam-edge signal are stored in advance in a table TA.
  • the table TA is for example stored beforehand in the flash ROM 400 .
  • step S 530 the CPU 100 references the data in the table TA to read out initial values for the respective counters 260 a to 260 c ; these readout initial values correspond to a current active edge appearing in the cam-edge signal. Then, the CPU 100 stores the readout initial values in the corresponding counters 260 a to 260 c , respectively in step S 530 .
  • the CPU 100 changes the information held by the cam-position determining flag F 2 from OFF to ON in step S 540 , proceeding to step S 570 .
  • step S 520 the CPU 100 proceeds to step S 570 while skipping the instructions in steps S 550 and S 560 .
  • step S 510 the CPU 100 shifts to step S 550 .
  • step S 550 If it is determined that the count value of the guard counter 260 b is equal to or greater than the product of the multiplication number f 2 (1200) and the number (6) of cylinders (the determination in step S 550 is YES), the CPU 100 goes to step S 560 . In step S 560 , the CPU 100 sets “0” to the count value of the guard counter 260 b , proceeding to step S 570 .
  • step S 550 the CPU 100 goes to step S 570 while skipping the instruction in step S 560 .
  • step S 570 the CPU 100 checks whether the count value of the guard counter 260 b is “0”.
  • step S 570 If it is determined that the count value of the guard counter 260 b is set to “0” (the determination in step S 570 is YES), the CPU 100 sends, to the angle clock module 260 , an instruction indicative of the enabling mode in step S 580 similar to step S 370 . This allows the reference counter 260 a to count in the enabling mode described above even if “0” is set to the count value of the guard counter 260 b.
  • step S 570 the CPU 100 sends, to the angle clock module 260 , an instruction indicative of the disabling mode in step S 590 similar to step S 420 . This permits the reference counter 260 a to count in the disabling mode described above.
  • step S 580 or S 590 the CPU 100 goes to step S 600 .
  • the CPU 100 checks whether the trigger active edge for the cam-edge interrupt task consists of an irregular region of the cam-edge signal in step S 600 . In other words, the CPU 100 determines whether the trigger active edge for the cam-edge interrupt task represents a change point Q or a change point located before or after a change point Q in step S 600 (S 610 , S 620 , and S 630 ).
  • the change points Q is a point at which the level of any one of the first cam signal and second cam signal transiently changes in the high-to-low direction while the other thereof is in the low level.
  • a change point P 1 at which the level of any one of the first cam signal and second cam signal transiently changes in the high-to-low direction while the other thereof is in the high level is a change point immediately before a change point Q.
  • a change point P 2 at which the level of any one of the first cam signal and second cam signal transiently changes in the low-to-high direction while the other thereof is in the low level is a change point immediately after a change point Q.
  • step S 600 the CPU 100 references the data of the table TA to determine whether the trigger active edge for the cam-edge interrupt task consists of an irregular region of the cam-edge signal based on the result of the reference.
  • step S 610 If it is determined that the trigger active edge represents a change point P 1 at which the level of any one of the first cam signal and second cam signal transiently changes in the high-to-low direction while the other thereof is in the high level (the determination in step S 610 is YES), the CPU 100 goes to step S 612 .
  • step S 612 like step S 412 , the CPU 100 sends, to the reference time selecting module 230 , an instruction to store, in the register 230 a , the edge-to-edge interval as the fixed time; this edge-to-edge interval is passed from the edge interval measuring module 220 in response to the trigger active edge for the cam-edge interrupt task.
  • the reference time selecting module 230 stores, in the register 230 a , the edge-to-edge interval as the fixed time.
  • step S 414 the CPU 100 sends, to the reference time selecting module 230 , an instruction to select, as the multiplication-clock reference time, the fixed time in step S 614 .
  • the reference time selecting module 230 transfers, to the multiplication clock generating module 240 , the fixed time stored in the register 230 a until an instruction to select, as the multiplication-clock reference time, the edge-to-edge interval is passed thereto from the CPU 100 .
  • step S 616 the CPU 100 sets, to the count value of the guard counter 260 b , a check-result value based on the determination in steps S 600 and S 610 . Thereafter, the CPU 100 exits the cam-edge interrupt task.
  • the product of “4.75” and the multiplication number f 2 which can be expressed by “ ⁇ (4+3 ⁇ 4) ⁇ f 2 ⁇ ”, is set to the count value of the guard counter 260 b as the check-result value based on the determination in steps S 600 and S 610 .
  • the product of “1.75” and the multiplication number f 2 which can be expressed by “ ⁇ (1+3 ⁇ 4) ⁇ f 2 ⁇ ” is set to the count value of the guard counter 260 b as the check-result value based on the determination in steps S 600 and S 610 .
  • step S 610 when the trigger active edge represents a change point Q at which the level of any one of the first cam signal and second cam signal transiently changes in the high-to-low direction while the other thereof is in the low level (the determination in step S 610 is NO and that in step S 620 is YES), the CPU 100 goes to step S 622 .
  • step S 622 the CPU 100 sends, to the reference time selecting module 230 , an instruction to store, as the fixed time, a value in the register 230 a .
  • the value to be stored in the register 230 a is obtained by correcting, based on a timing of a corresponding change point Q in the corresponding irregular region of the cam-edge signal, the edge-to-edge interval passed from the edge interval measuring module 220 in response to the trigger active edge for the cam-edge interrupt task.
  • the reference time selecting module 230 divides the edge-to-edge interval passed from the edge interval measuring module 220 in response to the trigger active edge for the cam-edge interrupt task by the ratio of a time interval between temporally adjacent change points P and Q to that between temporally adjacent change points P. In the embodiment, the ratio is obtained as “3 ⁇ 4”.
  • the reference time selecting module 230 stores, in the register 230 a , the obtained division as the fixed time.
  • step S 414 the CPU 100 sends, to the reference time selecting module 230 , an instruction to select, as the multiplication-clock reference time, the fixed time in step S 624 .
  • the reference time selecting module 230 transfers, to the multiplication clock generating module 240 , the fixed time stored in the register 230 a until an instruction to select, as the multiplication-clock reference time, the edge-to-edge interval is passed thereto from the CPU 100 .
  • step S 626 the CPU 100 sets, to the count value of the guard counter 260 b , a check-result value based on the determination in steps S 600 and S 620 . Thereafter, the CPU 100 exits the cam-edge interrupt task.
  • the trigger active edge represents a change point Q at which the level of the first cam signal transiently changes in the high-to-low direction while the second cam signal is in the low level.
  • the product of “5” and the multiplication number f is set to the count value of the guard counter 260 b as the check-result value based on the determinations in steps S 600 and S 620 .
  • the trigger active edge represents a change point Q at which the level of the second cam signal transiently changes in the high-to-low direction while the first cam signal is in the low level.
  • the product of “2” and the multiplication number f 2 is set to the count value of the guard counter 260 b as the check-result value based on the determinations in steps S 600 and S 620 .
  • step S 620 determines whether the trigger active edge represents a change point P 2 immediately after a change point Q (the determination in step S 620 is NO and that in step S 630 is YES). If the trigger active edge represents a change point P 2 immediately after a change point Q (the determination in step S 620 is NO and that in step S 630 is YES), the CPU 100 goes to step S 632 .
  • step S 632 the CPU 100 sends, to the reference time selecting module 230 , an instruction to correct the multiplication-clock reference time to be stored in the register 230 a.
  • the reference time selecting module 230 computes the sum of a previously passed edge-to-edge interval from the module 220 and an edge-to-edge interval passed therefrom next to the previously passed edge-to-edge interval, thus storing the computed value in the register 230 a as the multiplication-clock reference time.
  • step S 372 the CPU 100 sends, to the reference time selecting module 230 , an instruction to select, as the multiplication-clock reference time, the edge-to-edge interval in step S 634 , and thereafter exits the cam-edge interrupt task.
  • the reference time selecting module 230 transfers, to the multiplication clock generating module 240 , the edge-to-edge interval until an instruction to select, as the multiplication-clock reference time, the fixed time is passed thereto from the CPU 100 .
  • step S 630 the CPU 100 exits the cam-edge interrupt task while skipping the instructions in steps S 612 to S 632 .
  • the cam-position determining flag holds the information indicative of the default of OFF and the count value of the guard counter 260 b is incremented by 1 ⁇ f from the default of “0” (see sections e 10 and e 11 in FIG. 12 ). For this reason, the determination in S 510 is affirmative and the determination in step S 520 is negative, so that execution of the CPU 100 is shifted to the instruction in step S 570 .
  • step S 570 Because the count value of the guard counter 260 b is set to “1 ⁇ f”, which is not to “0”, the determination in step S 570 is NO, so that execution of the CPU 100 goes to the instruction in step S 600 via that in step S 590 .
  • step S 520 the cam-position determining flag F 2 holds the information indicative of the default of OFF and the count value of the guard counter 260 b is incremented by 1 ⁇ f from the count value “1 ⁇ f” so as to become “2 ⁇ f” (see sections e 12 in FIG. 12 ). This allows the determination in step S 520 to be affirmative.
  • the initial values which are determined based on the current active edge (E 32 ) in the cam-edge signal and the table TA, are stored in the corresponding counters 260 a , 260 b , and 260 c , respectively in step S 530 .
  • the initial values of 3600 equivalent to “3 ⁇ f”, 4800 equivalent to “4 ⁇ f”, and 3600 equivalent to “3 ⁇ f” are stored, as their count values, in the reference counter 260 a , the guard counter 260 b , and the angular counter 260 c , respectively (see the table TA in FIG. 11 ).
  • the cam-position determining flag F 2 is set to the information indicative of ON in step S 540 .
  • step S 570 because the active edge E 32 in the cam-edge signal does not represent a change point P 1 immediately before a change point Q, the determinations in steps S 610 to S 630 are all negative, then the cam-edge interrupt task is terminated.
  • step S 510 to S 630 are repeated until the determination in step S 610 is affirmative.
  • step S 610 when the next active edge E 33 whose next active edge corresponds to a change point Q appears in the cam-edge signal (see FIG. 12 ), the determination in step S 610 is affirmative.
  • step S 612 This permits the edge-to-edge interval to be stored in the register 230 a as the fixed time (see step S 612 ), and the fixed time is selected as the multiplication-clock reference time (see step S 614 ). Thereafter, the product of “4.75” and the multiplication number f 2 is set to the count value of the guard counter 260 b as the check-result value based on the determination in steps S 600 and S 610 (see a section e 13 in FIG. 12 ), and thereafter, the cam-edge interrupt task is terminated.
  • the multiplication clock generating module 240 generates, after the operation in step S 614 , the multiplication clock based on the fixed time until the edge-to-edge interval is selected in step S 634 .
  • step S 620 When the next active edge E 34 appears in the cam-edge signal (see FIG. 12 ), because the active edge E 34 represents a change point Q, the determination in step S 620 is affirmative.
  • the fixed time is selected as the multiplication-clock reference time (see step S 624 ).
  • the product of “5” and the multiplication number f 2 is set to the count value of the guard counter 260 b as the check-result value based on the determination in steps S 600 and S 610 (see the section e 14 in FIG. 12 ), and thereafter, the cam-edge interrupt task is terminated.
  • step S 630 When the next active edge E 35 appears in the cam-edge signal (see FIG. 12 ), because the active edge E 35 represents a change point P 2 immediately after the change point Q, the determination in step S 630 is affirmative.
  • step S 632 the multiplication-clock reference time is corrected (see “T 3 +T 4 ” in FIG. 12 ), and the edge-to-edge interval is selected as the multiplication-clock reference time in step S 634 (see a section e 15 ). Thereafter, the cam-edge interrupt task is terminated.
  • the multiplication clock generating module 240 generates, after the operation in step S 634 , the multiplication clock based on the edge-to-edge interval until the fixed time is selected in step S 614 or S 624 .
  • step S 550 is YES.
  • “0” is set to the count value of the guard counter 260 b in step S 560 .
  • step S 570 determines whether the reference counter 260 a executes the count-up operation in the enabling mode in step S 580 .
  • the operating mode of the reference counter 260 a is set to the enabling mode in step S 580 , For this reason, the reference counter 260 a continuously counts up until the count value reaches the upper limit stored in the first register 260 d (see a section e 15 in FIG. 12 ).
  • steps S 550 , S 570 , S 590 , S 600 , S 610 , S 620 , and S 630 are repeatedly executed by the CPU 100 each time an active edge appears in the cam-edge signal.
  • the repeated executions of the instructions in steps S 550 , S 570 , S 590 , S 600 , S 610 , S 620 , and S 630 are executed until it is determined that the count value of the guard counter 260 b has been increased to reach the product of the multiplication number f 2 (1200) and the number (6) of cylinders in step S 550 .
  • the ECU 1 is configured to generate the angle clock based on the crank signal or the cam-edge signal, and control at least one of the actuators associated with control of the engine based on a rotational position of the crankshaft CS specified by the count value of the angle clock.
  • the multiplication-clock reference time on which the multiplication clock is based is secured to the fixed time (see the operations in steps S 414 of FIG. 7 and S 614 of FIG. 10 ).
  • the angle clock is generated based on the fixed time as the multiplication-clock reference time.
  • the angle clock is generated based on the fixed time as the multiplication-clock reference time until the irregular region is terminated so that the edge-to-edge interval is set as the multiplication-clock reference time.
  • the angle clock generated based on the suitable value estimated at the end of an irregular region of the crank signal or the cam-edge signal can prevent an active edge of the angle clock from being delayed from a corresponding actual crank position of the crankshaft CS. This makes it possible to properly identify the operating conditions of the engine based on the count value of the angle clock, thus improving the accuracy of control of the engine.
  • step S 414 of FIG. 7 in step S 614 of FIG. 10 , or step S 634 thereof, the edge-to-edge interval passed from the edge interval measuring module 220 in response to the appearance of the trigger active edge for the crank-edge interrupt task or the cam-edge interrupt task is set.
  • the edge-to-edge interval measured by the edge interval measuring module 220 at the head of an irregular region of the crank signal or cam-edge signal is set.
  • the edge-to-edge interval measured by the edge interval measuring module 220 at the head of an irregular region of the crank signal or cam-edge signal represents appearance of a predetermined-directed level change in a part of the regular region of the crank signal or cam-edge signal; this part is located immediately before the corresponding irregular region.
  • the edge-to-edge interval measured by the edge interval measuring module 220 at the head of an irregular region of the crank signal or cam-edge signal is closer than any other edge-to-edge intervals measured before then. This results that the edge-to-edge interval measured by the edge interval measuring module 220 at the head of an irregular region reflects the level change in the irregular region of the crank signal or the cam-edge signal.
  • step S 414 of FIG. 7 setting, as the fixed time selected in step S 414 of FIG. 7 , in step S 614 of FIG. 10 , or step S 634 thereof, the edge-to-edge interval measured by the edge interval measuring module 220 at the head of an irregular region of the crank signal or cam-edge signal allows an angle clock on which the level change in the irregular region of the crank signal or the cam-edge signal to be generated based on the fixed time.
  • the edge-to-edge interval passed from the edge interval measuring module 220 in response to the end of an irregular region of the crank signal or the cam-edge signal is set as the multiplication-clock reference time (see step S 372 of FIG. 7 or step S 634 of FIG. 10 )
  • the multiplication-clock reference time (edge-to-edge interval) is corrected based on the period in the corresponding irregular region (see step S 380 of FIG. 7 or step S 634 of FIG. 10 ).
  • the multiplication clock generating module 240 works to generate an angle clock based on the edge-to-edge interval within the irregular region.
  • edge-to-edge interval within the irregular region represents a time interval between temporally adjacent active edges in the irregular region of the crank signal or the cam-edge signal, it may be different from an edge-to-edge interval within a regular region of the crank signal or the cam-edge signal.
  • the multiplication clock generating module 240 divides the multiplication-clock reference time by the multiplication number f to generate a multiplication clock (angle clock) whose clock cycle is a multiplication-number submultiple of the multiplication-clock reference time.
  • the clock cycle of the generated angle clock is different from that of an angle clock generated in a regular region of the crank signal or the cam-edge signal.
  • the multiplication clock generating module 240 immediately after the multiplication-clock reference time is reset to the edge-to-edge interval, the multiplication clock generating module 240 corrects the edge-to-edge interval passed from the module 220 based on an interval of the corresponding irregular region without directing using the edge-to-edge interval. After the correction, the multiplication clock generating module 240 divides the corrected edge-to-edge interval (multiplication-clock reference time) by the multiplication number f to generate a multiplication clock (angle clock) whose clock cycle is a multiplication-number submultiple of the corrected multiplication-clock reference time.
  • Counting the angle clock whose clock cycle is a multiplication-number submultiple of the corrected multiplication-clock reference time can prevent the count of the angle clock from being delayed from the count of an angle clock generated in a regular region of the crank signal or the cam-edge signal. This makes it possible to reduce the difference between a crank position of the crankshaft CS corresponding to the count value of an active edge of the angle clock generated in the irregular region and a corresponding actual crank position of the crankshaft CS.
  • step S 380 of FIG. 7 an edge-to-edge interval measured in an irregular region of the crank signal is corrected to a value obtained by:
  • the corrected edge-to-edge interval is stored in the first register 240 a as the corrected multiplication-clock reference time.
  • the product of an edge-to-edge interval measured in an irregular region of the crank signal and a ratio of a period between temporally adjacent active edges in a regular region thereof to a period temporally adjacent active edges in the irregular region represents an edge-to-edge interval to be measured in the regular region.
  • the edge-to-edge interval to be measured in the regular region satisfies that:
  • the ratio of the edge-to-edge interval measured in the irregular region to the edge-to-edge interval measured in the regular region is equal to the ratio of the period between temporally adjacent active edges in the irregular region to the period between temporally adjacent active edges in the regular region.
  • the edge-to-edge interval to be measured in the regular region corresponds to an edge-to-edge interval continuously measured in the irregular region only for a period temporally adjacent active edges in the regular region.
  • the correction of an edge-to-edge interval measured in an irregular region of the crank signal allows the corrected edge-to-edge interval to be approximated to an edge-to-edge interval to be measured in a regular region of the crank signal.
  • the ECU 1 when detecting that the crank signal is abnormal, the ECU 1 is configured to:
  • a clock cycle of a multiplication clock generated by the multiplication clock generating module 240 is changed from a value obtained by dividing, by the multiplication number f 1 (60) for the crank signal, the multiplication-clock time based on the first regular angle to a value obtained by dividing, by the multiplication number f 2 (1200) for the cam-edge signal, the multiplication-clock time corresponding to the second regular angle.
  • the multiplication number f 2 for the cam-edge signal is obtained by:
  • ⁇ 1 is the first regular angle
  • ⁇ 2 is the second regular angle
  • the multiplication number f 2 for the cam-edge signal is obtained to meet the equation 1.
  • the ratio of the multiplication number f 1 (60) for the crank signal to the first regular angle is matched with that of the multiplication number f 2 (1200) for the cam-edge signal to the second regular angle.
  • the clock cycle of the multiplication clock generated by the multiplication clock generating module 240 is constant although the multiplication number f is changed from the number f 1 for the crank signal to the number f 2 for the cam-edge signal and the period is changed from a value corresponding to the first regular angle to that corresponding to the second regular angle. This is because the ratio of the multiplication number f 1 (60) for the crank signal to the first regular angle is matched with that of the multiplication number f 2 (1200) for the cam-edge signal to the second regular angle.
  • change of the multiplication number f from the number f 1 for the crank signal to the number f 2 for the cam-edge signal allows the clock cycle of the multiplication clock generated by the multiplication clock generating module 250 to be constant.
  • the clock cycle of the multiplication clock to be used to operate the reference counter 260 a and the angular counter 260 c of the angle clock module 260 is kept constant before and after change of the input signal and the multiplication number f. This makes it unnecessary for the angle clock module 260 to execute specific tasks for switching its operations before and after change of the input signal and the multiplication number f.
  • crank signal cannot be input normally to the ECU 1 due to, for example, a break in wires connecting the crankshaft sensor 11 and the ECU 1 , the ECU 1 cannot identify the rotational position of the crankshaft CS.
  • the ECU 1 it is possible for the ECU 1 to continuously carry out proper control of the engine based on the cam-edge signal in place of the crank signal.
  • the multiplication-clock reference time to be referenced when the multiplication clock is generated is secured to the fixed value obtained by:
  • the “value based on the timing of the corresponding change point Q” is a ratio of a period in the irregular region between the trigger active edge for the cam-edge interrupt task and occurrence of a level change in the cam-edge signal to a period in a regular region of the cam-edge signal.
  • the division of the edge-to-edge interval passed from the module 220 by the ratio represents an edge-to-edge interval to be measured in the regular region.
  • the edge-to-edge interval to be measured in the regular region satisfies that:
  • the ratio of the edge-to-edge interval in the irregular region between the trigger active edge and occurrence of a level change in the cam-edge signal to an edge-to-edge interval of a regular region thereof is equal to the ratio of the period in the irregular region between the trigger active edge and occurrence of a level change in the cam-edge signal to a period in the regular region thereof.
  • the edge-to-edge interval to be measured in the regular region corresponds to an edge-to-edge interval continuously measured in the irregular region only for a period temporally adjacent active edges in the regular region.
  • the correction of an edge-to-edge interval measured in an irregular region of the crank signal allows the corrected edge-to-edge interval to be approximated to an edge-to-edge interval to be measured in a regular region of the cam-edge signal.
  • the multiplication clock generating module 240 divides the corrected edge-to-edge interval (multiplication-clock reference time) by the multiplication number f to generate a multiplication clock (angle clock) whose clock cycle is a multiplication-number submultiple of the corrected multiplication-clock reference time.
  • Counting the angle clock whose clock cycle is a multiplication-number submultiple of the corrected multiplication-clock reference time can prevent the count of the angle clock from being delayed from the count of an angle clock generated in a regular region of the cam-edge signal. This makes it possible to reduce the difference between a crank position of the crankshaft CS corresponding to the count value of an active edge of the angle clock generated in the irregular region and a corresponding actual crank position of the crankshaft CS.
  • step S 310 of FIG. 7 when the interrupt output from the pass-angle measuring module 250 is received, it is possible for the CPU 100 to determine that the trigger active edge represents the end of an irregular region of the crank signal or the cam-edge signal.
  • step S 400 of FIG. 7 it is possible to determine that a trigger active edge for the crank-edge or cam-edge interrupt task represents the head of an irregular region of the crank signal or cam-edge signal based on the count value of the angular counter 260 c.
  • the edge-to-edge interval passed from the module 220 in response to the trigger active edge for the crank-edge or cam-edge interrupt task is stored in the register 230 a , but the present invention is not limited to the structure.
  • a suitable value experimentally or logically estimated at the end of an irregular region of the crank signal or the cam-edge signal can be used.
  • the ECU 1 is configured to control the engine based on the crank signal when the crank signal is normal.
  • the ECU 1 can be configured to control the engine based on another signal consisting of at least one regular region and at least one irregular region.
  • step S 310 of FIG. 7 when the interrupt output from the pass-angle measuring module 250 is received, the CPU 100 determines that the trigger active edge represents the end of an irregular region of the crank signal or the cam-edge signal.
  • the present invention is not limited to the structure.
  • the CPU 100 can be configured to determine that the trigger active edge represents the end of an irregular region of the crank signal or the cam-edge signal when the count value of the angle counter 260 c becomes a value corresponding to an active edge appearing at the end of the irregular region of the crank signal or the cam-edge signal.
  • the CPU 100 is configured to determine that a trigger active edge for the crank-edge or cam-edge interrupt task represents the head of an irregular region of the crank signal or cam-edge signal based on the count value of the angular counter 260 c .
  • the CPU 100 can be configured to determine that a trigger active edge for the crank-edge or cam-edge interrupt task represents the head of an irregular region of the crank signal or cam-edge signal based on information except for the count value of the angular counter 260 c.
  • step S 600 of FIG. 10 the CPU 100 is programmed to determine whether the trigger active edge for the cam-edge interrupt task represents an active edge constituting an irregular region of the cam-edge signal based on the combination of the signal levels of the first and second cam signals, but the present invention is not limited to the structure.
  • the CPU 100 can be programmed to determine whether the trigger active edge for the cam-edge interrupt task represents an active edge constituting an irregular region of the cam-edge signal based on whether the count value of the angular counter 260 c becomes a value corresponding to an active edge appearing in an irregular region of the cam-edge signal.
  • an edge-to-edge interval measured at the head of an irregular region of the crank signal or the cam-edge signal is secured as the multiplication-clock reference time (see step S 414 of FIG. 7 and step S 634 of FIG. 10 ).
  • the angle clock is generated based on the secured edge-to-edge interval at the end of the irregular region of the crank signal or the cam-edge signal.
  • the signal-level changes in the rank signal or the cam-edge signal may be greatly different before and after the start of an irregular region of the crank signal or the cam-edge signal. This may result that the edge-to-edge interval at the head of an irregular region of the crank signal or cam-edge signal can not sufficiently reflect the change in the signal levels in the irregular region of the crank signal or the cam-edge signal.
  • the multiplication-clock reference time is not merely fixed to an edge-to-edge interval at the start of an irregular region of the crank signal or the cam-edge signal, but can be fixed to a previously corrected edge-to-edge interval at the start of the irregular region.
  • the microcomputer 30 can correct the edge-to-edge interval based on predetermined correction rules in steps S 412 , S 612 , and S 622 . Thereafter, the microcomputer 30 can store, in the register 230 a , the corrected edge-to-edge interval as the fixed multiplication-clock reference time. It is preferable that the microcomputer 30 can correct an edge-to-edge interval at the end of an irregular region of the crank signal or the cam-edge signal based on predetermined correction rules in steps S 380 and S 632 .
  • the predetermined correction rules can be freely determined to allow an edge-to-edge interval at the head of an irregular region or during an irregular region of the crank signal or the cam-edge signal to be properly corrected.
  • the predetermined correction rules can be designed to correct, to a value, an edge-to-edge interval when the trigger active edge for the crank-edge or cam-edge interrupt task represents the head of an irregular region of the crank signal or the cam-edge signal or is locates within the irregular region; this value is obtained by multiplying the edge-to-edge interval by a predetermined coefficient.
  • an edge-to-edge interval when the trigger active edge for the crank-edge or cam-edge interrupt task represents the head of an irregular region of the crank signal or the cam-edge signal or is locates within the irregular region to be corrected to the product of the edge-to-edge interval and the predetermined coefficient.
  • the corrected edge-to-edge interval can be secured as the fixed multiplication-clock reference time.
  • the predetermined coefficient can be experimentally or logically determined, or can be determined based on parameters when the trigger active edge for the crank-edge or cam-edge interrupt task represents the head of an irregular region of the crank signal or the cam-edge signal or is locates within the irregular region.
  • the predetermined correction rules can be freely determined to correct an edge-to-edge interval at the head of an irregular region or during an irregular region of the crank signal or the cam-edge signal based on another edge-to-edge interval previously determined before the irregular region.
  • the predetermined correction rules allow an edge-to-edge interval in response to the trigger active edge to be corrected based on a previous edge-to-edge interval measured before the trigger active edge.
  • the corrected edge-to-edge interval can be secured as the fixed multiplication-clock reference time; this fixed multiplication-clock reference time can be referenced by the multiplication clock generating module 240 when the module 240 generates the multiplication clock.
  • an edge-to-edge interval at the head of an irregular region of the crank signal or the cam-edge signal can be corrected by adding thereto a value; this value is obtained by multiplying, by a coefficient less than 1, an edge-to-edge interval measured immediately before the irregular region.
  • the signal level in regular regions of the crank signal or the cam-edge signal before the irregular region is expected to be rapidly changed.
  • a signal-level change is expected to appear in an edge-to-edge interval before the irregular region of the crank signal or the cam-edge signal.
  • INT(i) represents the edge-to-edge interval (i)
  • INT(i ⁇ 1) represents the edge-to-edge interval (i ⁇ 1).
  • step S 412 of FIG. 7 is schematically illustrated in the timing chart of FIG. 13 .
  • INT(j) represents the edge-to-edge interval (j)
  • INT(j ⁇ 1) represents the edge-to-edge interval (j ⁇ 1).
  • INT(m) represents the edge-to-edge interval (m)
  • INT(m ⁇ 1) represents the edge-to-edge interval (m ⁇ 1)
  • INT(m ⁇ 2) represents the edge-to-edge interval (m ⁇ 2).
  • INT(n) represents the edge-to-edge interval (n)
  • INT(n ⁇ 1) represents the edge-to-edge interval (n ⁇ 1).
  • step S 612 and S 622 of FIG. 10 is schematically illustrated in the timing chart of FIG. 14 .
  • INT(P) represents the edge-to-edge interval (p)
  • INT(p ⁇ 1) represents the edge-to-edge interval (p ⁇ 1)
  • INT(p ⁇ 2) represents the edge-to-edge interval (p ⁇ 2).
  • the cam-edge signal is used to generate the multiplication clock in place of the crank signal, but the present invention is not limited to the structure.
  • either the first cam signal or the second cam signal can be used to generate the multiplication clock.
  • the edge interval measuring module 220 for example can measure a period between temporally adjacent active edges with regular angular intervals (at regular change points) in the first cam signal except for irregular change points with respect to the regular angular intervals.
  • the edge interval measuring module 220 for example can measure a period between temporally adjacent active edges in the second cam signal with regular angular intervals (at regular change points) except for irregular change points with respect to the regular angular intervals.
  • the edge interval measuring module 220 can directly use the cam signal to measure a period between temporally adjacent active edges in the cam signal.
  • the counters are designed to count up, but can be designed to count down.
  • the counters and the registers of the angle clock generating unit 200 can be implemented as hardwired logical circuits installed in the microcomputer 30 .
  • each of the input circuit 10 and the output circuit 20 can be implemented as hardware logical circuits, software modules, or a hardware/software integrated system installed in the microcomputer 30 .
  • the tasks (1) to (4) to be executed by the CPU 100 can be implemented as hardware logical circuits or a hardware/software integrated system.
  • the present invention is capable of being distributed as program products, for example, the programs stored in the flash ROM 400 in a variety of forms. It is also important to note that the present invention applies equally regardless of the particular type of signal bearing media used to actually carry out the distribution. Examples of suitable signal bearing media include recordable type media such as CD-ROMs and DVD-ROMs, and transmission type media such as digital and analog communications links.

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  • General Engineering & Computer Science (AREA)
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  • Electrical Control Of Ignition Timing (AREA)
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EP1953376A3 (fr) 2009-09-23
JP2008190344A (ja) 2008-08-21
EP1953376A2 (fr) 2008-08-06
JP4274253B2 (ja) 2009-06-03
EP1953376B1 (fr) 2012-11-28

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